1. Field of the Invention
The present invention relates to a method for manufacturing a metal structure having different heights formed on a semiconductor substrate. For example, a portion of the metal structure is used for a semiconductor element, and another portion of the metal structure, having a different height, is used for packaging of the semiconductor element.
2. Description of the Related Art
Generally, a certain fine metal structure used for a semiconductor element needs to be packaged for protection. To accomplish this, a second fine metal structure having a height higher than the fine metal structure is usually formed on both sides of the fine metal structure for packaging the element.
FIG. 1A through FIG. 1F are drawings illustrating a general method for forming the metal structure, having different heights, for the element and packaging. Referring to FIG. 1A to FIG. 1F, the conventional method for manufacturing the metal structure having different heights will now be described.
As shown in FIG. 1A, a seed layer 2 is formed on a semiconductor substrate 1, and a first plating mold 3 having a plurality of first grooves 3a is formed through a photolithography process. The seed layer 2 is a base layer for the plating process that will be described later.
A metal is used to fill in the first grooves 3a of the first plating mold 3 through the plating process, and then, the first plating mold 3 is removed so that a first metal structure 4, having a predetermined height, that will be used for the element is formed as shown in FIG. 1B.
As shown in FIG. 1C, a second plating mold 5, having a plurality of second grooves 5a, is formed through a photolithography process on the semiconductor substrate 1 on which the first metal structure 4 is formed.
As shown in FIG. 1D, a metal is used to fill in the second grooves 5a of the second plating mold 5 through the plating process, and then, the second plating mold 5 is removed so that a second metal structure 6, having a height greater than the first metal structure 4, is formed as shown in FIG. 1E.
Finally, the unnecessary seed layer 2 is removed so that the first metal structure 4 and the second metal structure 6, having different heights with respect to each other, are formed on the semiconductor substrate 1 as shown in FIG. 1F.
In the construction of the metal structure manufactured through the foregoing processes, the first metal structure 4 is used for a semiconductor element and the second metal structure 6, disposed on both sides of the first metal structure 4, is used in packaging for the protection of the element.
However, since the conventional method for manufacturing a metal structure having different heights requires a complicated photolithography process and a plating process that must be performed twice, respectively, in the formation of the first plating mold 3 and the second plating mold 5, the whole process becomes very complicated.
Furthermore, in the conventional method, the formation of the second plating mold 5, for forming the second metal structure 6, and the corresponding plating process is performed after the first metal structure 4 is formed, therefore, the formation of the second plating mold 5 is influenced by the shape of the first metal structure 4. Thus, the process becomes very difficult and troublesome. Additionally, the substrate 1 can be contaminated due to the frequent photolithography processes, and the plating for the second metal structure 6 may become unstable.
Furthermore, if the first and the second metal structures 4 and 6 are formed with different materials, then, the seed layer 2 should be removed after the first metal structure 4 is formed and a second seed layer (not shown), which is a base layer for the formation of the second metal structure 6, should be formed. Here, a dedicated layer, such as an insulating layer, for protecting the first metal structure 4 should be provided when forming the second seed layer. Therefore, the conventional process becomes even more complicated.